Can I have Hound check my entire repository all at once?

Sorry, but no, and we don't recommend doing so. Our rule is "Don't rewrite existing code to follow the style guide." See the thoughtbot style guide.

It can be dangerous to re-write a lot of code for just style reasons. It can introduce functional regressions, which are a higher-level concern than style.

We believe the right approach is to convert a codebase over time, one pull request at a time, to conform to a style guide. Only focus on style in diffs and make smaller changes that ideally have tests associated with them.

If you'd still like to analyze your whole repo, try using Rubocop locally.